To apply various processing, such as testing or examination, onto workpieces, such as semiconductor chips, these workpieces are conveyed through a plurality of processing stages. To allow the workpieces to be efficiently conveyed and be efficiently subjected to such processing, use is made of a general-purpose tray (user tray) that can contain a plurality of workpieces at the same time and a special-purpose processing tray (test tray) that differs from the general-purpose tray in, for example, containing pitch and that has a lock mechanism that locks workpieces (see Japanese Unexamined Patent Publication No. H7-198779, for example).
In detail, each general-purpose tray that contains a plurality of workpieces arranged thereon is successively conveyed to follow various processing stages. In a predetermined transferring area, a plurality of unprocessed workpieces are taken out from the general-purpose tray in one lump, and are transferred to a processing tray. The processing tray that contains the unprocessed workpieces are then transported to a processing area (test area) in which unprocessed workpieces undergo a predetermined processing. The processing tray containing the workpieces that have undergone the predetermined processing in the processing area is again transported to the transferring area. The workpieces that have undergone the predetermined processing are again returned to the general-purpose tray, and are conveyed to follow the next processing stage.
In the transferring area in which workpieces are transferred, unprocessed workpieces and processed workpieces are transferred while a tray holding device is holding one processing tray. Therefore, the processing tray is required to wait without being transported to the processing area until these workpieces are completely transferred. As a result, the processing time becomes long as a whole, and there is a limit to the improvement of productivity.
Therefore, a possible method for solving these problems is to arrange a plurality of processing trays on a plane in the tray holding device, to provide a plurality of transporting devices that transport processing trays between the transferring area and the processing area, and to transport the processing trays at the same time. However, this method merely brings about an increase in size of the tray holding device, an increase in cost, and an increase in installation space that is required to install the device. Accordingly, this method makes it difficult to achieve a decrease in size of the device, consolidation, a decrease in cost, space-saving, etc.
The present invention has been made in consideration of these circumstances. It is, therefore, an object of the present invention to provide a tray holding device that is capable of achieving structural simplification, mechanical consolidation, size reduction in the entire device, space-saving in installation space, or shortening of a processing-time as a whole which is brought about by, for example, shortening a waiting time, that is capable of efficiently applying various processing, such as testing, examination, measurement, treatment, or assembling, onto workpieces, such as semiconductor chips, substrates, or other electronic parts, and that is capable of heightening productivity.